That small, silky pouch stuck to your wall is almost certainly a spider egg sac, not a cocoon in the traditional sense. Spiders don’t spin cocoons the way moths do. Instead, they wrap their eggs in silk to protect them while they develop. The shape, size, color, and location of the sac can tell you a lot about which spider left it there and whether you need to worry.
What You’re Actually Looking At
Spiders produce egg sacs by wrapping dozens or even hundreds of eggs in layers of silk. These sacs can look like small cotton balls, flat discs, teardrop-shaped pouches, or tight little pillows depending on the species. They’re typically white, off-white, tan, or pale yellow, and they range from the size of a pea to roughly the size of a marble. When you find one attached to a wall or ceiling, it usually means a female spider chose that spot as a safe, sheltered place to leave her next generation.
Each sac can contain anywhere from a dozen to several hundred baby spiders. That’s why dealing with them matters. One overlooked egg sac in a corner can lead to a noticeable spike in spider activity a few weeks later once the spiderlings emerge and disperse.
Yellow Sac Spiders: The Most Common Wall Culprit
If you’re finding small silk pouches in the upper corners of rooms, behind picture frames, or along the edge where your wall meets the ceiling, there’s a good chance yellow sac spiders are responsible. These nocturnal spiders are roughly the size of a nickel and are one of the most common indoor species in North America. They build small silk retreats to hide in during the day and can spin a new one in just 10 to 15 minutes.
Yellow sac spiders also use silk structures for their eggs. The female lays eggs about 14 days after mating, places them in a silken sac, and guards them until they hatch. One species (Cheiracanthium mildei) strongly prefers human-made structures for egg-laying, which is why these sacs turn up indoors so frequently. Once the eggs hatch, the young spiderlings continue using the sac as a daytime hiding spot, venturing out only at night to hunt.
These spiders do bite, and the bite is painful, so removing both the spider and its egg sacs is a reasonable step. You won’t typically see the spider during the day since it stays tucked inside its silk retreat.
Other Spiders That Leave Egg Sacs Indoors
Cobweb spiders (the family that includes common house spiders) are another frequent source of wall-mounted egg sacs. Their sacs tend to be round, papery, and brownish, often suspended within a messy, tangled web in a corner or along a window frame. A single female can produce multiple egg sacs over her lifetime, each holding dozens of eggs.
Cellar spiders, the long-legged spiders you see hanging upside down in basements and garages, take a different approach. Females carry their egg sacs in their mouthparts rather than attaching them to a surface. Each sac holds roughly 13 to 60 eggs for long-bodied species, or 10 to 27 for short-bodied species. If you see a loose, thin cluster of eggs near a cellar spider web, it likely belongs to one of these.
Brown recluse spiders also produce egg sacs, but they tend to place them in dark, undisturbed spaces like closets, storage boxes, and behind furniture rather than on open walls. If you live in an area where brown recluses are common and you find a sac in a secluded spot, it’s worth identifying the spider before handling it.
How to Remove Spider Egg Sacs Safely
A vacuum cleaner is the simplest and most effective tool. It removes the sac intact, preventing spiderlings from scattering. After vacuuming, seal and dispose of the vacuum bag or empty the canister into a sealed plastic bag outdoors. A broom works too, but crushing the sac can release spiderlings if they’ve already developed.
Destroying egg sacs is the most important part of spider control indoors. Each sac can contain hundreds of young spiders, and removing the adults without dealing with the eggs means you’ll be right back where you started within weeks. Check the spots where walls meet ceilings, behind picture frames, inside light fixtures, and in the corners of closets and garages. These are the places spiders favor most.
Keeping Spiders From Coming Back
Routine, thorough cleaning is the single most effective deterrent. Spiders prefer quiet, undisturbed areas, so regular vacuuming and dusting of corners, baseboards, closets, basements, and attics makes your home less inviting. Reducing clutter in storage areas removes the sheltered spots spiders look for when choosing where to settle.
Sealing entry points is the next priority. Gaps under doors are one of the most common ways spiders get inside. Installing door sweeps and making sure window screens fit tightly blocks most of them. Outside, trim back any shrubs, vines, or tree limbs that touch the house, since these act as bridges that let spiders walk right onto the structure. Move firewood, stacked materials, and debris away from the foundation.
Lighting choices also make a difference. Standard outdoor bulbs attract night-flying insects, which in turn attract the spiders that eat them. Switching to yellow or sodium vapor bulbs at exterior entrances draws fewer insects and reduces the food supply that brings spiders close to your home. For additional protection, a perimeter insecticide spray around door thresholds, foundation vents, garage entrances, and the bottom edge of siding can discourage spiders from crossing into the structure. These treatments typically need to be reapplied monthly or every other month during warmer seasons.